“Woah! It's like Spotify but for academic articles.”

Instant Access to Thousands of Journals for just $40/month

Get 2 Weeks Free

Stoichiometry of N-Methyl-d-Aspartate Receptors Within the Suprachiasmatic Nucleus

Stoichiometry of N-Methyl-d-Aspartate Receptors Within the Suprachiasmatic Nucleus Abstract The circadian pacemaker within the suprachiasmatic nucleus (SCN) confers daily rhythms to bodily functions. In nature, the circadian clock will adopt a 24-h period by synchronizing to the solar light/dark cycle. This light entrainment process is mediated, in part, at glutamatergic synapses formed between retinal ganglion afferents and SCN neurons. N -methyl- d -aspartate receptors (NMDARs) located on SCN neurons gate light-induced phase resetting. Despite their importance in circadian physiology, little is known about their functional stoichiometry. We investigated the NR2-subunit composition with whole cell recordings of SCN neurons within the murine hypothalamic brain slice using a combination of subtype-selective NMDAR antagonists and voltage-clamp protocols. We found that extracellular magnesium (Mg o ) strongly blocks SCN NMDARs exhibiting affinities and voltage sensitivities associated with NR2A and NR2B subunits. These NMDAR currents were inhibited strongly by NR2B-selective antagonists, Ro 25-6981 (3.5 μM, 55.0 ± 9.0% block; mean ± SE) and ifenprodil (10 μM, 55.8 ± 3.0% block). The current remaining showed decreased Mg o affinities reminiscent of NR2C and NR2D subunits but was highly sensitive to Zn o , a potent NR2A blocker, showing a ∼44.2 ± 1.1% maximal inhibition at saturating concentrations with an IC 50 of 7.8 ± 1.1 nM. Considering the selectivity, efficacy, and potency of the drugs used in combination with Mg o -block characteristics of the NMDAR, our data show that both diheteromeric NR2B NMDARs and triheteromeric NR2A NMDARs (paired with an NR2C or NR2D subunits) account for the vast majority of the NMDAR current within the SCN. Copyright © 2010 the American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Neurophysiology The American Physiological Society

Loading next page...
 
/lp/the-american-physiological-society/stoichiometry-of-n-methyl-d-aspartate-receptors-within-the-G0SeB3804u

You're reading a free preview. Subscribe to read or print the entire article.

And millions more from thousands of peer-reviewed journals, for just $40/month

Get 2 Weeks Free

To be the best researcher, you need access to the best research

  • With DeepDyve, you can stop worrying about how much articles cost, or if it's too much hassle to order — it's all at your fingertips. Your research is important and deserves the top content.
  • Read from thousands of the leading scholarly journals from Springer, Elsevier, Nature, IEEE, Wiley-Blackwell and more.
  • All the latest content is available, no embargo periods.

Stop missing out on the latest updates in your field

  • We’ll send you automatic email updates on the keywords and journals you tell us are most important to you.
  • There is a lot of content out there, so we help you sift through it and stay organized.